signal clippin???

[daymean]

hey guys jus wonderin about this thing....
whats signal clippin?
when does it occur??
what can it damage???
can n e one or everyone help??

[daymean]

how can this be tested???

[Sully]

the simplest way is to use a scope.

[daymean]

when it starts 2 sound distorted?
can signal clippin occur while using say an amp dat has less power than the rated power of the subwoofer (rms power)

[SR]

only if you are trying to overdrive the amplifier to attempt to get the sub to play louder

[Terabyte]

Usually too much power will drive the speaker to its excursion limits very quickly....resulting in strange mechanical sounds.
Here's a good way to test your amplifier's output......
Measure the output voltage of the amplifier playing a test tone on the sub (use a multimeter...set to ac volts)
Use the formula P=V^2/R to get an idea of how much power is being put out at that frequency.
e.g. if the output voltage is 50V and the load impedance is 2 ohms, the power would be (50X50)/2 =1250W.
It's generally a good practice to adjust your system so that this value is a close match with the rating of your sub.......unless you really know what you're doing.

N.B. this power only applies for that particular frequency, so it doesn't make sense testing using a 100Hz tone when you will be using the sub for 80Hz and below.....also music can contain very dynamic content capable of a wide range of frequencies and levels.....make sure your enclosure is designed to handle them!!

[TK!]

get a test cd ... with tones... play em... soft at first, cranking up volume... clipping with one freq is easy to hear. with music> not easy at all.

[SR]

This is a guide that will attempt to explain the relationship between the various volume affecting devices in car audio. you should be able to relate to most of this.

first, lets discuss a standard amplifer. it takes an AC voltage input, has two DC voltage "rails", and uses power from the DC rails to create an AC signal that is between the two voltage rails in magnitude. bridging is a technique that allows both rails to be used on all parts of the wave, and thus you can get an output voltage that is up to twice as high as the rail voltages.

Clipping... basically imagine you and a friend have a jump rope in a hallway and start spinning it. so if you spin it tightly, the jump rope (AC output) will stay between the walls (DC rails). spin it harder and the rope will begin to slam aginst the walls and won't be able to travel further. ok, this is pretty much an everyday analogy to clipping. the output VOLTAGE is supposed to be larger then maximum allowed values.

Clipping and Amplifiers - clipping does stress the power supply of the amplifer and still puts a lot of current through the transistors. pretty much clipping will heat up an amp. (i'm talking about standard amps). generally the clipping isn't pure square wave either, and the amplifer will spend more time making power and less time resting.

[SR]

Clipping as distortion -- Clipping distorts the sound, this often sounds muddy, buzzy, springy, or such. lows will not sound as low. similar effects can happen if your speaker moves past Xmax, but generally clipping is avoidable. If the music sounds distorted in this manner, it may be from clipping.

Clipping as Compression -- Clipping compresses waves, and this is why it is moderately desireable for the general public. basically if you have 3 notes, each louder then the one before it, a higher amount of gains to cause more clipping will make each note almost equal in volume, but the normally louder notes will be more distorted. One common fact is that woofer distortion is less offensive, even at statistically high amounts. So a little bit of clipping will make notes on average a little louder but not much more distorted. this of course is bad for dynamic range as all notes will begin to sound similar in volume... so the SQ guys probably want to stay away from clipping, while the street guys should become familiar with it and find the best SPL-distortion level.

Clipping and fast notes -- if notes follow very closely, clipping can blur them for the same reason above. basically the notes will not decay to a high enough degree before the next one starts, so instead of 5 fast notes you can get 5 wobbles in a single note...

[SR]

Clipping and Tweeters -- Clipping damaged tweeters. this is a proven fact from pro audio. basically, tweeters are rated at 100+ watts, but in reality work with maby 5... Clipping causes a lot of fast transistion, and the "Fourier Transform" shows that there will be more high frequency components -- the distortion! so if the tweeter can take 10 watts, and gets 5 from the amp and 5 from clipping, well, it can become damaged! this problem is lessened by using seperate amplifers for components and woofers, and using the active crossovers provided with the amplifers to remove bass from the components and vocals from the woofers. Recently i showed someone this effect by distorting some computer woofers -- at full gain he SWORE it was fullrange, but with the gains cut a bit there was just bass.



Ok, now for the next fun part...

Volume knob Vs gain knob. biggest difference is that the volume knob should be made unique, and as a referance for the rest of the system -- gains should be set around the volume knob and not vice-versa!

What i mean by all this is that there should be one volume knob. if you want to change volume you should just turn the SINGLE knob and be done. you should not need to adjust the bass EQ and gains on 2 or more amplifers to change volume!

[SR]

so what happens when i turn my gains all the way up? well at 10/30 the system is REALLY loud. wow, cool, i've still got 20 ticks left! 15/30, hmm, a bit distorted. 20/30 Very distorted, i'm afraid to hear what 30/30 sounds like! anyone who's played with car audio knows what i'm talking about -- "look how loud it gets, and it's only at 10!". so sad...

so what would happen if i cut gains a bit? well, at 10/30 it would be modestly loud, at 20/30 it would be very loud, and it would start distorting at 25 or 30. i can now change my volume over maby 25 of the 30 ticks. the guy above can only go over 15 of the ticks before it craps out! and what's more ironic is that the guy above probably spent extra to get 4v preouts that won't ever go above 1V because the gains are so mis-set!


ok, and now for bass enhancments. this is pretty much an artistic area. you can boost the signal strenght at certain tones. this means that you will clip easier at some frequencies. so you can get more distortion at some areas and less at others. if gains are cut a bit more, bass enhancements and EQs can have a role in adjusting the tonality, so long as you realize that it will affect how the sound transitions from normal to distorted. generally these settings are abused though.

HU clipping = BAD. the HU has a preout, and this preout is what provides a signal to the amps. this is similar to a small VOLTAGE amplifer. the preout provides no power to the output of the amplifer, and uses very little power to send the signal. it has the same problmes with the DC rails though. well, if you pump the volume and bass enhancements to the max, you can clip the signal to the amplifer. so now ANY gain setting will have distortion!

these are all related. in general you'll have to make multiple passes while setting gains and volume and bass enhancments. volume should be set first, followed by bass enhancements and then gains. and then go back and re-set the bass enhancments, then the volume if needed... ect.

[SR]

oh, and the ever controversial:

Clipping and woofers: there's more power in the output signal when you clip your output. not overly good for any speaker and while subs are less affected, they often succumb.

Severe clipping isn't good for anything. low amounts of clipping can work for most people on the streets.

Headroom - some people get 1kW amps and only use 100 watts. the extra 10dB is headroom. this means that there will be less chance of clipping on those transient notes.

also

Clipping and output devices - tube clip different then MOSFET and BJT devices. many people call BJTs grainy, despite their great statistical performance.

[Hook]

gr8 info there sr

it sound sticky-ish..put it in a separate thread nuh

[SR]

no i not puttin up no more sticky on this forum again
men does complain bout it
workin with duanne on somthing else but like both ah we stickin right now
soon though all them stickies will be in an informative section of this website

[daymean]

hear nah sr i have ah question...
my deck is 4volt out
but my max volume is 60 or 65 i eh sure and the installer tell me i shoulden raise my volumer beyond 28-30
am i utilising my 4 volt out....
i eh sure if this question is at all valid
just kindda confused about the post u did above
but GREAT INFO DUDE!!!

[Terabyte]

If you've got a 4 volt non-clipping output on the deck, then you are doing yourself a great injustice by not maximizing its potential to send as clean a signal to your amplifiers as is possible.
Simply put...your installer eh know wha he doin....
Higher voltage from the deck means a higher signal to noise ratio ....ie less noise....especially induced noise in the signal cables.
The first part of proper level setting in any audio system is turning the deck up to around 75% max volume (in your case somewhere in the 40's).
Input sensitivity for the other components can then be adjusted using that 75% reference value as your highest playable volume.
If the deck has a non-clipping output...ie the manufacturer guarantees against clipping distortion in the signal...at ANY volume...you can probably use an even higher setting.
The key is to keep amplifier gains as low as possible.....since these have a wonderful tendency to amplify any noise in the system.
Hope this clears up an misconceptions......

[SR]

i agree with tera
installer doesnt understand the principles of line level matching